The Oklahoma Independent Petroleum Association (OIPA) has released a study of pneumatic controller emissions at Oklahoma oil and gas production facilities, giving the industry and regulatory agencies a better understanding of the impact those controllers have on air quality.

Pneumatic controllers are used to maintain process conditions such as liquid level, pressure, delta pressure, and temperature. Separate types of pneumatic controllers can be used for other applications such as monitoring and activating safety systems or controlling plunger lift systems.

Emissions from oil and natural gas production sites are calculated for a variety of environmental analyses ranging from federal rulemakings, state air quality emissions inventories and greenhouse gas reporting. Because of the large number of production sites and the complexity of emissions profiles, pneumatic controller emissions are estimated in these analyses rather than measured directly.

In the study, OIPA found an average pneumatic controller emissions rate of 1.05 standard cubic feet natural gas/hour, which is significantly lower than previous studies. Previous estimates were significantly overinflated — 5 to 27 times higher than the OIPA study.

“Previous studies put pneumatic controllers as one of the top emission sources for the oil and natural gas industry,” Hatfield said. “Those emissions didn’t exist in the field. They only existed on paper because of incorrect previous estimates.”

The study included 172 randomly selected oil and gas production sites from the Oklahoma assets of eight OIPA companies. The sites contained 205 producing wells and 680 pneumatic controllers. Sample sizes for previous studies ranged from several dozen to several hundred pneumatic controllers.